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Java > Open Source Codes > org > mr > kernel > BlockingMessageListener


1 /*
2  * Copyright 2002 by
3  * <a HREF="http://www.coridan.com">Coridan</a>
4  * <a HREF="mailto: support@coridan.com ">support@coridan.com</a>
5  *
6  * The contents of this file are subject to the Mozilla Public License Version
7  * 1.1 (the "License"); you may not use this file except in compliance with the
8  * License. You may obtain a copy of the License at
9  * http://www.mozilla.org/MPL/
10  *
11  * Software distributed under the License is distributed on an "AS IS" basis,
12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13  * for the specific language governing rights and limitations under the
14  * License.
15  *
16  * The Original Code is "MantaRay" (TM).
17  *
18  * The Initial Developer of the Original Code is Amir Shevat.
19  * Portions created by the Initial Developer are Copyright (C) 2006
20  * Coridan Inc. All Rights Reserved.
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22  * Contributor(s): all the names of the contributors are added in the source
23  * code where applicable.
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25  * Alternatively, the contents of this file may be used under the terms of the
26  * LGPL license (the "GNU LESSER GENERAL PUBLIC LICENSE"), in which case the
27  * provisions of LGPL are applicable instead of those above. If you wish to
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32  * If you do not delete the provisions above, a recipient may use your version
33  * of this file under either the MPL or the GNU LESSER GENERAL PUBLIC LICENSE.
34  
35  *
36  * This library is free software; you can redistribute it and/or modify it
37  * under the terms of the MPL as stated above or under the terms of the GNU
38  * Lesser General Public License as published by the Free Software Foundation;
39  * either version 2.1 of the License, or any later version.
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41  * This library is distributed in the hope that it will be useful, but WITHOUT
42  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
43  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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45  */

46
47 package org.mr.kernel;
48
49 import org.mr.MantaException;
50 import org.mr.IMessageListener;
51 import org.mr.core.protocol.MantaBusMessage;
52 import org.mr.core.protocol.MantaBusMessageConsts;
53
54 /**
55  * BlockingMessageListener gives a synchronized ability to IMessageListener
56  * you can sent a request and wait for a response with this object
57  * @see org.mr.MantaAgent for example
58  * @since Jan 19, 2004
59  * @version 1.0
60  * @author Amir Shevat
61  *
62  */

63 public class BlockingMessageListener implements IMessageListener {
64      MantaBusMessage response = null;
65      MantaBusMessage returnResponse = null;
66      MantaBusMessage request;
67      String JavaDoc listenerString;
68      Object JavaDoc syncObject = new Object JavaDoc();
69      
70      public BlockingMessageListener(MantaBusMessage request){
71         this.request = request;
72      }
73      
74      public BlockingMessageListener(){
75         
76      }
77      
78     /* (non-Javadoc)
79      * @see org.mr.IMessageListener#onMessage(org.mr.core.protocol.MantaBusMessage)
80      */

81     public void onMessage(MantaBusMessage message) {
82         
83         synchronized(syncObject){
84             while (response != null) {
85                 try {
86                     syncObject.wait();
87                 } catch (InterruptedException JavaDoc e) {
88                     e.printStackTrace();
89                 }
90             }
91             response = message;
92             syncObject.notifyAll();
93         }
94     }//onMessage
95

96     /**
97      * waits untill onMessage is called with the response to the request
98      * @param timeout after this time in milli we stop blocking
99      * @return the response messages
100      * @throws InterruptedException
101      * @throws MantaException
102      */

103     public MantaBusMessage waitForResponse(long timeout) throws InterruptedException JavaDoc, MantaException{
104         if(request != null && request.getHeader(MantaBusMessageConsts.HEADER_NAME_SENT_FAIL) != null)
105             throw new MantaException("Failed to send request, no use to wait for response.",MantaException.ID_WAIT_FOR_RESPONSE_FAIL );
106         
107         synchronized(syncObject){
108             if(response != null) {
109                 return response;
110             }
111             if(response == null) {
112                 syncObject.wait(timeout);
113             }
114             returnResponse = response;
115             response = null;
116             syncObject.notifyAll();
117         }
118         return returnResponse;
119     }
120     
121     
122     /**
123      * @return Returns the listenerString.
124      */

125     public String JavaDoc getListenerString() {
126         return listenerString;
127     }
128
129     /**
130      * @param listenerString The listenerString to set.
131      */

132     public void setListenerString(String JavaDoc listenerString) {
133         this.listenerString = listenerString;
134     }
135
136 }
137
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